It is known that flame retardancy of a plant can be accomplished through the use of various chemicals, often complex bromine containing compounds, by means of coating, wetting, injecting, immersing, spraying or some other means of applying the flame retardant chemical to the exterior of the plant. Such exterior application could coincidentally include some penetration of the plant's foliage or shallow penetration of the woody parts, but the methods are predominantly external application. In contrast, the present invention uses a method of systemic infusion which imparts flame retardancy through an internal application.
It is also known that preservation of foliage, parts of plants or plants themselves has been claimed through a process of external immersion, in contrast to the present invention which systemically infuses an aqueous solution. Several patents describe preservation through immersion, such as Sheldon et al, U.S. Pat. No. 3,895,140; Romero-Sierra et al, U.S. Pat. No. 4,278,715; Romero-Sierra et al, U.S. Pat. No. 4,328,256; Bakker, French Pat. No. 1,105,091 and Barhala, French Pat. No. 2,160,310. All of these listed patents differ from the present invention in that none involve the principal use of systemic infusion and none involve the introduction or treatment of a plant or plant part in any manner with a flame retardant.
A similar process to the present invention is found in Nordh, U.S. Pat. No. 4,243,693. However, the Nordh patent does not teach or suggest the introduction of a flame retardant, but rather merely the introduction of a preservative.
External application of flame retardant materials creates a covering or coating on the plant that is often unattractive and obvious. Thus, methods which externally apply flame retardant material often leave the plant foliage with a chalky, waxy or unnatural looking surface or sticky feeling to the touch.
One of the present inventors is aware of a process for imparting flame retardant property to a plant part. Such previously known process involved the total immersion of a plant part in a solution containing at least 22% by weight of magnesium chloride in combination with approximately 20% glycerin or polyethylene glycol 200 for approximately seven days, rinsing, drying overnight and subsequently dipping the above treated plant part in a coating solution for restoration of color at least partially lost in the previous immersion step. The preferred amount of magnesium chloride in the above process was 27% by weight.
In contrast, the current invention discloses a process for imparting at least flame retardant property to a plant, or plant part, through systemic infusion and using significantly less magnesium chloride to impart flame retardancy. Additionally, the current invention allows simulation of the plant's original color through the use of a dye in the systemically infused aqueous solution without a subsequent coating step.
An article entitled, The Effects of Additives on Freshness and Flammability of Christmas Trees, John F. Ahrens and George R. Stephens (Connecticut Experiment Station, Bulletin 760, Dec. 1975), teaches away from the use of aqueous chemical additives for the increase in flame retardancy over the use of water alone. The article compared the use of additives such as potassium chloride and material containing ions of potassium, aluminum sulfate, chloride and other chemicals with the use of water alone for measurement of properties including flame retardancy. In the experiments, varieties of trees were placed in water alone, water containing one of the various chemical additives, hot water or allowed to stand without water. The results showed little or no advantage through the use of chemical additives over water alone for flame retardancy.
Lastly, a short publication or bulletin entitled, Focus on Floriculture, Purdue Univeristy, Cooperative Extension Service, Vol. 11(2), May 1983, pages 8-9, briefly discusses the use of an ammonium sulfate additive to water used for maintaining a tree, specifically a Christmas tree. This publication does not reflect the present invention since it neither substantiates that the presence of the ammonium sulfate adds to the degree of fire resistance over water only, as evidenced in the above-cited article, nor does the publication reflect the present invention, because of the continued presence of the water and additives in this publication.
The prior art does not teach or suggest the present invention because of the uncertain nature of the uptake of material by a plant. The Nordh patent does not teach or suggest the ability to systemically infuse flame retardant material, since such material differs in characteristics and properties from those materials systemically infused under the Nordh patent. Additionally, other prior art regarding immersion, dipping or spraying do not teach or suggest the present invention since such external applications do not tackle nor solve the problems of internally or systemically infusing material despite the uncertainty of results when dealing with the complex plant vascular system.
Additionally, prior art concerning the addition of material to water to act as a flame retardant either did not show any improvement over the use of water only, which teaches away from this invention, or did not demonstrate flame retardant properties in a plant which had been permanently removed from an aqueous solution or any other source of water.